In Italian Patent Application No. 3376 A/87 filed on the same date by the present Applicants (corresponding to my U.S. application Ser. No. 07/154,782 filed 10 Feb. 1988), an automatic machine is described, for the continuous production of dual-use filter sachets for infusion products having bags or pouches for containing successive fractional doses of the said products. This machine comprises along the production line means designed to progressively fold and longitudinally seal a tubular strip of thermally weldable filter paper fed with the fractional doses, being in a flattened tubular form and horizontally oriented, and for thermally welding the tube transversely so as to enclose the fractional doses between two of the successive transverse thermal welds. Downstream thereof is a means with rotating wheels having pickup elements for applying to the flattened tube equidistantly spaced labels as wall as a longitudinally continuous thread transversely contacting said labels, and stickers or tabs of thermally weldable material across the alternate transverse thermal welds partly to the back of said labels. Further downstream is a means for cutting up the said tube thus conformed into portions comprising at least two bags and for setting-up these bags and sealing together their extremities.
More particularly, such a dual-use filter sachet with multiple successively or serially arranged bags or pouches each containing a corresponding fractional dose or unit quantity of the infusion product, has a structure allowing for two modes of use, one in the flattened form for collating in lots for the sale thereof with said bags or pouches in superimposed arrangement or stacked back to back by folding one bag or pouch over or adjacent to the other and one in an unfolded or extended arrangement of the said pouches following an action of pressing and pulling the corresponding label covering the handling thread of said filter sachet by the user. The said thread has a length which substantially equals the length of the filter sachet when the latter is in its unfolded arrangement of use of its bags or pouches by action of the user. The thread is fastened to the opposite extremity of the sachet by means of a sticker or tab made of a thermally weldable material jointly with the label made of a not thermally weldable material and is arranged to surround longitudinally the outside of the sachet when the said bags or pouches are in their collated bulk arrangement for sale with folded-back pouches.